gdb: check if pid is valid

Add check to make sure pid is valid.
Remove stack check for interrupt context.

Signed-off-by: xuxingliang <xuxingliang@xiaomi.com>

tools/gdb/nuttxgdb/thread.py

@@ -366,7 +366,11 @@ class Nxthread(gdb.Command):
                         g_registers.restore()
 
         else:
-            if arg[0].isnumeric() and pidhash[int(arg[0])] != 0:
+            if (
+                arg[0].isnumeric()
+                and int(arg[0]) < npidhash
+                and pidhash[int(arg[0])] != 0
+            ):
                 if pidhash[int(arg[0])]["task_state"] == gdb.parse_and_eval(
                     "TSTATE_TASK_RUNNING"
                 ):